Sensors for underground duct probes have been used in the past for detecting ultrasonic vibrations in underground ducts. Such ultrasonic vibrations are generally due to the leaking of air or other gases in pressurized sheaths around underground cables in the ducts. A sensor for this use is normally attached to the front end of a flexible carrier comprised of a number of interconnected rods.
Heretofore, conventional sensors for this purpose have been complex in construction in that they are highly specialized and require a considerable amount of circuitry. Because of such conventional probes, a need exists for improvements such that the sensors will be simpler in construction, and easier to use, yet are removable from their carriers so as to allow for variations in the applications to which they are put.